In the conventional manufacture of methoxyisopropylamine, methoxyisopropanol is contacted with ammonia in the presence of a catalyst under amination conditions to produce methoxyisopropylamine and byproduct water. One of the problems in the recovery of the methoxyisopropylamine from the reaction mixture is that an azeotrope consisting of about 14% water and 86% methoxyisopropylamine is formed and thus creates a problem in the recovery of the methoxyisopropylamine from the reaction product. As is known, there are many procedures for breaking azeotropes. For example, one may adjust pressure or contact the azeotrope with another consolidation component which forms a lower boiling azeotrope with one of the compounds in the mixture. In the case of an organic in water azeotrope, one often may add a hydrocarbon as the codistillation agent to aid in the separation.
One of the problems associated with the methoxyisopropylamine-water azeotrope is that it is extremely difficult to produce a methoxyisopropylamine product which is essentially anhydrous, e.g., less than about 1% water. Any residual water in the methoxyisopropylamine tends to affect its usefulness as a reactant in many chemical reactions.
The following patents illustrate various approaches to the separation of amine-water azeotropes.
U.S. Pat. No. 4,868,335 discloses the recovery of mono-n-hexylamine from a mono-n-hexylamine-water azeotrope. To effect separation, the azeotrope is contacted with di-n-hexylamine or a mixture of di-n-hexylamine and tri-n-hexylamine. The di-n-hexylamine forms a lower boiling azeotrope with water and is removed by distillation. The organic phase then can be separated from the aqueous phase by decanting.
U.S. Pat. No. 3,433,788 discloses a process for recovering amines from aqueous solutions by solvent treatment and distillation. In particular the invention pertained to processes for the recovery of morpholine from aqueous solutions wherein the N-alkylmorpholines and some other amines form an azeotrope with water which could not be separated. Dewatering techniques involving the addition of sodium hydroxide were suggested, however, it was pointed out that the sodium hydroxide had to be recovered and that large amounts of water had to be removed by distillation. Ethyl ether was disclosed as being an extractant for morpholine but was unsatisfactory because of losses due to the high volatility of ethyl ether. The patentees suggested the utilization of an inert, water-immiscible, selective liquid organic solvent as an extractant. Specifically the extractants listed were organic vehicles which were inert to the amine and had a boiling point higher than the amine compound. Solvents included aliphatic alcohols, saturated aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, saturated ketones, ester derivatives of ethyl and diethyleneglycol, alkylphosphoric acids, alkylcarboxylic acids, and alkylamines.
U.S. Pat. No. 3,033,864 discloses a process for recovering alkanolamines from mixtures containing hetrocyclic nitrogen compounds such as piperazines by azeotropic distillation. In the process, the mixture of pyrazine or piperazine and alkanolamines were fractionally distilled with a codistillation agent whereby the lower boiling azeotrope of the codistillation agent and alkanolamine were separated as distillates and the residue or bottoms enriched with respect to pyrazine and piperazine. Representative codistillation agents included aliphatic hydrocarbons, aromatic hydrocarbons and nuclear chlorinated aromatic hydrocarbons.